Associate Professor Daniel Ortiz-Barrientos

Associate Professor

Overview

In the Ortiz-Barrientos Lab we study the genetics of speciation and adaptation. We have developed a new system of research to study the replicated evolution of traits and reproductive isolation, the early stages of speciation and the origin of ecotypes, and the molecular causes of reproductive isolation and adaptation. We are also interested in the role of sexual selection on plant speciation, and on the evolution of sexual recombination. Please visit our pages to learn more about our research, our team members, and about adaptation and speciation in the Senecio lautus species complex.

Research Interests

The ecological and genetic basis of speciation.As populations adapt to new environmental challenges they may become reproductively isolated from such other populations. The genetic changes associated with the evolution of reproductive isolation remain largely unknown, and therefore we have a limited understanding as to how ecology and genetics interact during the origin of new species. In the Ortiz-Barrientos lab we are tackling this problem by studying the early stages of speciation in the S. lautus species complex (sensu lato). Specifically, we are interested in identifying those genes responsibles for hybrid failure under field conditions, and in discovering their function within species. We use a combination of genomic, quantitative and classical genetics, together with reciprocal transplant experiments in our research.

The genetics of adaptation.In his famous treatise on natural selection, Ronald A. Fisher argued that "The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time". The genetic basis of traits contributing to fitness remains largely unresolved, particularly because some times many alleles of small effect control phenotypic variability, and because sometimes traits may evolve in step with other traits. These putative features of genetic architectures and trait evolution make the genetic study of adaptation difficult and impossible in most organisms. In our lab we are using mapping by selection of extreme tails to identify those genes responsible for ecotypic differences, and those traits responsible for fitness differences in the wild. Further, we are investigating the adaptive significance of genetic correlations during ecotypic divergence, and the relative contributions of additive vs. non-additive effects to fitness variation.

The genetic basis of parallel evolution.Populations experiencing similar selective pressures may evolve similar traits. As they adapt to similar environments, populations may fix similar alleles, or they might reach a phenotypic solution via different biochemical and genetic routes. In the Ortiz-Barrientos lab we are investigating how maritime populations of S. lautus have repeatedly and independently adapted to contrasting habitats along the Australian coast. We are using population genomic approaches (e.g., using RAD tags) and mapping by selection experiments to identify those genomic regions responsible for the replicated evolution of tall and prostrate forms in S. lautus. We combine these results with the use of Nearly Isogenic Lines to test the adaptive significance of candidate genes under field conditions.

Experimental evolution.Direct demonstration for the role of natural selection in the creation of new speciation is rare. Although microbial and unicellular eukaryotic organisms have provided insights as to how speciation occurs, there are very few examples in plants and animals as to how natural selection creates reproductive isolation. in the Ortiz-Barrientos lab we are exploring various strategies to deconstruct species and then to use natural selection to reconstruct them. Using specific quantitative genetic breeding designs together with QTL mapping we are tracking genetic changes that take place as adaptation proceeds and reproductive isolation revolves (e.g., the evolution of immigrant inviability and ecologically dependent postzygotic isolation). Results from these experiments will shed light on the connection between adaptation and speciation, and will help us understand how genetic architectures evolve.

Ortiz-Barrientos, Daniel, Grealy, Alicia and Nosil, Patrik (2009) The genetics and ecology of reinforcement: Implications for the evolution of prezygotic isolation in sympatry and beyond.
Annals of the New York Academy of Sciences,
1168 156-182. doi:10.1111/j.1749-6632.2009.04919.x

Possible Research Projects

Note for students: The possible research projects listed on this page may not be comprehensive
or up to date. Always feel free to contact the staff for more information, and also with your own research ideas.